THERMAL COOLING EXPERIMENT:
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A resistor on the -Z axis could serve as a heat sink for excess
solar power and would be a good study project for students. Sizing
the resistor to dissipate all solar power in excess of the nominal
average power could allow us to get rid of about 3 watts of heat.
If we don't do anything, then that 3W adds to our peak temperature.
If we switch it to a radiating resistor, then that gives us at least some
thermal control. Assuming the total solar flux is about 140W through
our spacecraft, this would give us about a 3.5% control range. Taking
the 4th root at a nominal 270 deg K operating temperature, then this
could equate to a temperature difference of about 3 degrees?
Just my guess.....
So we put 80 RED LEDS on the bottom of PC sat as a 3W thermal radiator
for this test. And just for fun, at night we can also turn them on as
power permits as a visual experiment. Calculations suggest a magnitude
of about 6 if it is pointing straight down. Eight, if it is off to
one side or the other. Magnitude 8 is visible with binoculars.
Bob Bruninga, WB4APR